The foams are dispersions of gas in a small amount of a liquid and have a broad field of application at industrial scale. In the oil industry, the use of foam has been extended to naturally-fractured reservoirs and their main applications has been focused to reduce the produced gas in oil wells completed below the gas-oil contact and to increase the oil recovery factor in enhanced oil recovery processes. In those applications, the stability of the foam plays a paramount role and it depends on the chemical structure of the used surfactant, as well as the temperature, pressure and salinity conditions in the oil reservoir.
The patents that support the main surfactants that have been used to generate foams with application to enhanced oil recovery processes are:
a) U.S. Pat. No. 5,273,682 for Alkyl aryl sulfonate,
b) U.S. Pat. No. 5,049,311 for the Alkoxy-alkyl-benzenesulfonate,
c) U.S. Pat. No. 4,607,695 for Alpha olefin sulfonate
d) U.S. Pat. No. 7,104,327 for Betaines and
e) Report DE-FC26-03NT15406 of the US Department of Energy. for the alkyl ether sulfonate.
The stability of the generated foams by using those surfactants, decreases drastically in some reservoir because their harsh conditions, with temperatures that goes higher than 70° C., salinities higher than 30,000 ppm of STD, and of divalent ions concentrations such as calcium and magnesium, higher than 2,000 ppm.
The following patents are formulations of foaming agents with improved properties to tolerate high concentrations of divalent ions and/or temperature, and therefore, increase the stability of the foams, which are:
1. U.S. Pat. No. 952,474, It is a foam used to improve the sweeping efficiency during the injection of steam or carbon dioxide in oil reservoirs, which are constituted by at least one producing well and one injector well. First, steam is injected until breakthrough occurs in the producing well. Then, a mixture of vapor, non-condensable gas and an aqueous solution of surfactant-polypeptide (sodium salts, ammonium of sulphated ethoxylated alcohols, ethoxylated linear alcohols, linear toluene sulfonates) is injected.
2. U.S. Pat. No. 5,295,540, foams based method for improving the production of hydrocarbons in underground reservoir, which consists of injecting steam and fluids produced within the formation and injecting a mixture of vapor, a non-condensable gas and an aqueous mixture of surfactant and polysaccharides such as linear toluene sulphonates, alkylaryl sulphonates, dialkylaryl sulphonates, alpha olefin sulphonates and alpha olefin sulphonate dimerizers.
3. U.S. Pat. No. 4,703,797, which consists on the generation of a foam where the displacement fluid is dispersed in an aqueous based solution of surfactant. Being the foam, a surfactant blend based on lignosulfonates with anionic, non-ionic and amphoteric surfactant, in order to improve the sweeping efficiency in enhanced oil recovery processes.
4. U.S. Pat. No. 3,939,911, System of three surfactants, Alkyl or alkylarylsulfonate which is a water soluble salt, as a surfactant the phosphate ester with average PW less than 1000 UMA, another surfactant with sulfobetaine base; applied to improved recovery processes in formation waters of 200 to 14,000 ppm of dissolved polyvalent ions (Ca, Mg), this combination being stable up to a temperature of 107° C., resistant to bacteria and inhibits the formation of scale.
5. U.S. Pat. No. 7,104,327, methods for fracturing high-temperatures subterranean oil-bearing formation with a viscous, aqueous, foamed fracturing fluids, made with water, a terpolymer of 2-acrylamido-2-methylpropane sulfonic acid, acrylamide and acrylic acid or salts, a gas, a C8-C22 foaming agent alkylamido-betaine, alpha-olefin sulfonate, trimethyl-taloyl-ammonium chloride, C8-C22 alkylethoxylated sulfate and trimethyl-coco-ammonium chloride. Cocoamidopropylbetaine is mentioned as a special foaming agent and a viscosity breaker for viscosity control. The use of mixtures of alkylamido-betaine and alpha olefinsulfonates to produce foams is not mentioned, nor does it increase the stability of the foams.
6. Paper: Improving the foam performance formobility control and improved sweep efficiency in gas flooding. He mentions that the stability and apparent viscosity of a foam generated by alpha olefinsulfonates in brine of 30,000 and 120,000 ppm of STD, is improved when formulated with partially hydrolyzed polyacrylamide base polymers or xanthan gum type biopolymers. It was also mentioned, that the stability of the foam generated with the twelve carbon alpha olefinsulfonates is substantially increased when formulated with surfactants of the amine oxide type.
It has been reported (Langmuir 2000 16, 7173, Langmuir 2004 20, 9945) the synergistic effect achieved by using alkylamidopropyl betaine with anionic surfactants of sodium alkyl ether sulfate and sodium alkyl sulfate types. It was remarked the capacity of the alkylamidopropyl betaines to stabilize and to improve the rheological properties (viscosity) of the generated foams, which have application in shampoos and conditioners for hair.
In the paper: Synergistic sphere-to-rodmicelle transition in mixed solutions of sodiumdodecyl sulfate and cocoamidopropylbetaine (Langmuir 2004 20,565-571) indicates that the synergistic effect between cocoamidopropylbetaine and sodium dodecyl sulfate is due to an electrostatic attraction between the heads of both surfactants.
Patent US 2007/0142235 A1, protects a composition and process of recovery of hydrocarbons, which consists of injecting an aqueous solution into the production formation, through one or more injection wells, pushing the solution within the formation to recover the hydrocarbon. The aqueous solution is composed of one or more amphoteric surfactants of the alkylamidobetaine type which form a viscoelastic surfactant gel which can simultaneously reduce the interfacial tension and increase the viscosity of the injected fluid in certain oils and brines. Viscoelastic gels are tolerant to electrolytes and multivalent cations and are useful in reservoirs that have medium to high temperatures, high salinities, high concentrations of divalent ions and low porosity. It also indicates that the secondary surfactant can be from the anionic, cationic or non-ionic group and that the polymer providing the viscosity can be from the group of polyacrylamide, partially hydrolyzed polyacrylamide, xanthan gum, hydroxyethyl cellulose or guar gum. It also mentions that the combination of alkylamidobetaine with secondary surfactants of the linear type sodium dodecylbenzenesulfonate and sodium arylalkyl-allyl sulfonate reduces the interfacial tension and increases the viscosity of the system. It does not mention the use of amphoteric surfactants based on alkylamidobetaines and their mixtures to generate foams, nor the mixtures of alkylamidobetaines and anionic surfactants of the alpha olefin sulfonate type.
In none of the above references claim the use of foaming additives that apply the synergistic effect of sodium alpha olefinsulfonates and alkylamidopropyl betaines for the development of formulations that are stable in environments of high salinity and temperature.
In the patents MX 2008015989 and WO 2010068082 the advantage of formulations of foams working efficiently in environments of high salinity, temperature and a high concentration of divalent calcium and magnesium ions is stated, in addition to the foam formed having a higher stability with respect to to that generated by the products that are used worldwide as described in the aforementioned patents. Derived from these patents 2 foaming products were generated called:                IMP-ESAT-1000 (salinity 120,000 ppm STD, temperature 100° C.)        IMP-ESAT-2000 (salinities up to 250,000 ppm STD, temperature 100° C.)        
Given the chemical characteristics of the raw material that make up the IMP-ESAT-1000 and 2000 products, they support temperature and salinities up to 100° C. and 85,000 ppm STD respectively, and therefore given the extreme field conditions of salinity and temperature in Mexico, that exceed the aforementioned values, a new formulation was developed that allows to extend its tolerance to new salinity conditions higher than 254,000 ppm SDT and temperatures up to 150° C.